A variety of electronic devices include at least one battery as a power source. In some instances, the battery provides auxiliary or backup power while a different source such as house current provides main power to the device. In many instances, a battery or perhaps a set of several batteries provide all of the power necessary to operate the electronic device. Any device that relies on a battery for either auxiliary or main power is susceptible to low battery issues.
In some cases, loss or impending loss of battery power can be annoying but is of little or no real significance. Examples of such situations include battery-powered hand held games and remote controls for audio/visual equipment such as stereos and televisions. When the game ceases to function or the remote no longer operates the stereo or television, a user can simply replace the battery or batteries.
In other cases, however, the loss or impending loss of battery power can have significant detrimental impact. An example of such a situation includes information storage devices such as a PDA (personal digital assistant). While many such devices have rechargeable batteries or include a main battery source and a backup battery source, these devices often still can be susceptible to battery problems.
Another example of a situation in which the loss or impending loss of battery power would have a negative impact includes devices that are part of security systems. Security systems can include a variety of components that for convenience are battery-powered yet contain data that has been entered by a user or an installation expert. The loss of such data could be an inconvenience. Worse, it is conceivable that the loss or impending loss of battery power in particular security systems devices could render the security system at least partially inoperable.
Yet another example of a situation in which the loss or impending loss of battery power can have a significant negative impact includes electronic devices known as controllers. Typical electronic controllers can be battery-powered and can be configured to control or operate a variety of different systems and/or equipment. An HVAC system is an example of such a system that can be controlled by a battery-powered controller. An HVAC controller can be used to regulate a variety of home heating, cooling and ventilating equipment such as furnaces, boilers, air conditioners, air exchangers, humidifiers, dehumidifiers, filtration units, UV lamps, and the like. Some HVAC controllers are considered to be thermostats.
Loss of battery power in an HVAC controller can have multiple impacts. Many HVAC controllers are user-programmable to include a number of time and temperature set points. Loss of battery power can cause a loss of these set points, which can require the user to tediously re-enter a relatively large amount of data. A loss of battery power can in some instances cause the HVAC controller to lose its ability to receive signals from and/or send command signals to various pieces of equipment in the system. This can mean, for example, that the furnace may shut down on a cold winter day or the air conditioning may shut down on a hot mid-summer day. Clearly, these are undesirable consequences.
Some battery-powered devices include attempts at warning a user that a loss of battery power is imminent. For example, some devices such as thermostats, detect a first low voltage level of a battery, and display a “REPLACE BATTERY” message on the display of the thermostat at a first blink rate. When a second lower voltage level is subsequently detected, the thermostat begins blinking the “REPLACE BATTERY” message at a higher blink rate. When a third lower voltage level is detected, the thermostat may stop operating and turn all control outputs to the off position, and display only the blinking “REPLACE BATTERY” message and not any other control parameters. These features are provided in, for example, the Chronotherm III product family of thermostats, available from the assignee of the present invention. It has been found, however that users often do not heed or even notice such warnings until the thermostat stops operating.
Thus, a need remains for methods of indicating a low battery condition within an electronic device such that a user actually takes notice of the indication. A need also remains for controllers adapted to indicate a low battery condition in such a way so that a user takes the appropriate actions in replacing the battery.